The present invention relates to a high frequency module for use in, for example, a radio communication apparatus as a high frequency signal processing device and, more particularly, to a high frequency module having a circuit board carrying electronic parts thereon, an insulating member covering the circuit board, a metal film or shield formed on the insulating member, and electrodes, and a method of producing the same.
A problem with a conventional radio communication apparatus is that spurious radiations (wave leakage) from a high frequency processing circuit, e.g., oscillation circuit turn round to cause the other circuits to oscillate also. Another problem is that noise causes the apparatus to malfunction. To eliminate these problems, it has been customary to provide the oscillation circuit with a shield. The shield is implemented by, for example, metal plates which are bonded together in a partitioning structure. This kind of shield is used to shield a high frequency amplifier circuit, oscillation circuit, control circuit or similar device. Specifically, a metal plate is soldered at one end to a ground pattern provided on a circuit board which carries electronic parts thereon, thereby surrounding the device. Another metal plate covers the top of the device. The metal plates, e.g., silver-plated copper plates have their adjoining ends connected together by screws or rivets or by solder. However, this kind of approach has a drawback that the shield structure is complicated and troublesome to produce, resulting in an increase in cost.
In light of the above, Japanese Patent Laid-Open Publication No. 59-186397 teaches a composite IC (Integrated Circuit) made up of a plurality of molded modules. The molded modules are mounted on a circuit board and electrically connected together by a circuit pattern to constitute desired circuitry. However, this approach brings about another problem that spurious radiations occur from the circuit pattern, which interconnects the modules, and affect the other circuits or even an external apparatus.